How do I know what size tank my floor can support?

[WishyFishy]

Hi,

I live in an old house with pine hardwood flooring that is admittedly not in the best shape. I'm sort of planning a 20 or 29gal but I only really have 2 options on where to put it, either:

-on said hardwood flooring-- it does bend a little in places when you walk on it

-on carpet (not my preferred spot haha)

Should I be worried about the weight of a 20 or 29 (I would rather go with the 29) on the floor if I have a well-made stand that's level? I'm 90% sure my house is not on a concrete slab but I can check and confirm that. Most of the resources I've found on this issue are dealing with 55-125 gallon tanks so I appreciate any insight! I don't know if a 20-29 is enough weight to be concerned about.

[Fish Folk]

As a "rule of thumb" I always just add a zero for lbs. i.e. -- A 20 runs about 200 lbs with substrate, hardscape, etc. 29 gal. is about 290 lbs. If you think about a full grown person . . . or a couple persons . . . standing where you want your tank to be, that's about how to estimate things.

I advise knowing which way the boards run underneath the floor. There are typically large braces that support any flooring. Normally, they run from the outside walls of a room across towards the opposite outside wall. Like the ribs of a ship, they cross from port to stern. If you think about your home / apartment / etc looking down from on top, the boards usually run across from side to side -- the shortest distances. If you can get underneath, you'll actually see.

Anyway, you want to think about setting the tank up against a wall that is stood on block with boards supporting the weight of a stand. It should be absolutely fine.

Always safest to put tanks in a basement though.

Yes, a 125 requires good planning.

[Andy's Fish Den]

I have always done as @Fish Folksaid, adding a zero to the end as an estimate of the weight of a tank, or multiply by 10. Also, as a general rule of thumb, most floors in a house can hold at least a 55 gallon tank safley without any worries. If you are going any larger, I would suggest finding which way the floor joists run and placing the tank perpendicular )across) to them. Another trick to help spread the weight out is to have a piece of 1/2-3/4" plywood cut slightly larger than the footprint of the stand and put that down on the floor and then set the stand and tank of it, and it will help spread out the weight. 

[gardenman]

The floor moving when you walk on it is a bad omen. You have to remember that the weight of the tank is a long term issue. Over time, wood tends to deflect when subjected to a load placed upon it. In engineering you're talking about static and dynamic loads. In the building trades they're often referred to as dead or live loads. A filled aquarium is a static/dead load. The materials under a filled aquarium never get a chance to relax. You walking across the floor is a dynamic/live load. The floor is only stressed momentarily and can then rebound when you move away. Wood tends to rebound from temporary live loads. A static load on wood over the long term can erase that ability to rebound and cause permanent issues. (Bentwood rockers are made by subjecting wood to a static load over time and they don't unbend when the load is removed.)

In general, putting a tank against an exterior wall is safer than putting one in the middle of a floor. Older homes (pre 1920's) tend to have been built stronger than much newer construction. (Though there are exceptions.) The more you can disperse the load, the better. Setting the stand on some thicker plywood or lumber can help. I wouldn't worry a lot about a 20 or 29 gallon tank but anything much larger could be an issue.

[WishyFishy]

Thank you everyone! This is a future project, probably for sometime next year, so I was just looking into if it is possible at all. Maybe the carpeted spot would be better since that is on an exterior wall.

Unfortunately I do not have a basement or I would put my tanks down there, and it would be easier to check the joists! I think the tank would be perpendicular to them in the preferred place based on the way the house is laid out-- wouldn't make sense any other way. I will see about finding alternative places for it too to avoid that section of the floor with boards that flex. The house is about ~1920s.

[anewbie]

On 3/7/2023 at 8:20 AM, gardenman said:

The floor moving when you walk on it is a bad omen.

The floors that you walk on generally are not part of the support system; old wood floors that are poorly installed will frequently develop some wiggle due to expansion/contraction of wood over time; but it has zero effect on actual weight the structure can support. 

 

Generally speaking if a floor can't support a 29; it won't be able to support the football team you invite over friday to party with.

 

The only catch is what will happen when you invite the football team over to look at the aquarium; then you might get into trouble. Once you go larger than 29 things can begin to get more serious. A 40 can be over 450lbs and a 120 is well over 1000 lbs; but a 29 is still in the rein of the er excessively chubby person taking a forever nap in the rocking chair.

 

Having said this before you buy an aquarium; check your home owners policy; an aquarium that breaks and dumps water on a wood floor can easily cause $20,000 in damage.

Edited March 8, 2023 by anewbie

[nabokovfan87]

On 3/6/2023 at 9:16 PM, Fish Folk said:

As a "rule of thumb" I always just add a zero for lbs. i.e. -- A 20 runs about 200 lbs with substrate, hardscape, etc. 29 gal. is about 290 lbs. If you think about a full grown person . . . or a couple persons . . . standing where you want your tank to be, that's about how to estimate things.

here is water weight for aqueon.

On 3/7/2023 at 1:06 PM, WishyFishy said:

Unfortunately I do not have a basement or I would put my tanks down there, and it would be easier to check the joists! I think the tank would be perpendicular to them in the preferred place based on the way the house is laid out-- wouldn't make sense any other way. I will see about finding alternative places for it too to avoid that section of the floor with boards that flex. The house is about ~1920s.

as for tanks on wood floors, the only thing I've heard is to make sure the legs of the stand are on the beams of the floor.  If you don't position it that way, you could end up with an issue over time of things moving on you.